Machine for making an anti-static tire tread

ABSTRACT

A method of providing an extruded tire tread (T) with anti-static properties. In this method, a pin ( 10 ) is coated with an electrically conductive material (M). The coated pin ( 10 ) pierces the tire tread (T) to form an opening ( 12 ) of the desired depth and then is withdrawn. During withdrawal of the pin ( 10 ), the material (M) remains in the pierced opening ( 12 ) so that a conductive body ( 14 ) is formed in the tire tread (T). The pin ( 10 ) can then be re-coated with the material (M) and the cycle repeated to produce a plurality of conductive bodies ( 14 ) in the tire tread (T).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application Ser. No.11/451,211 filed on Jun. 12, 2006, which is a divisional of U.S.Application Ser. No. 10/235,474 filed on Sep. 4, 2002, which claimspriority to U.S. Provisional Application No. 60/317,000 filed on Sep. 4,2001. The disclosures of all of the above applications are incorporatedby reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to a method for making an anti-static tiretread and a machine for performing this method.

BACKGROUND OF THE INVENTION

During operation of a vehicle, electric charge can be conducted to earththrough the tires provided that the tires have a sufficient level ofconductivity. Without this conductivity, a moving vehicle is susceptibleto the build-up of static electric charge which can negatively affectelectronic circuitry, interfere with radio reception, create unwantedsparks, and/or cause personal discomfort. Tires are constructed ofnatural and synthetic rubbers which are electrical insulators.Accordingly, conductive materials (e.g., carbon black mix) are commonlyintroduced into a tire to increase its electrical conductivity andthereby avoid the build-up of static electric charge. For example, in amethod disclosed in U.S. Pat. No. 6,183,581, a carbon black mix in avolatile liquid is poured into through-holes in a central region of atire tread. When the volatile liquid evaporates, the carbon black mix isleft inside the holes to create electrically conducting bodies whichform electrical bridges between the tire's rolling surface and itscarcass. The entire disclosure of this patent is hereby incorporated byreference.

SUMMARY OF THE INVENTION

The present invention provides a method for making an anti-static tiretread comprising the steps of coating a pin with an electricallyconductive material, piercing the tire tread with the coated pin to forman opening, and withdrawing the pin from the now-formed opening in thetire tread. The electrically conductive material remains within theopening during the withdrawing step so that an electrically conductivebody is formed in the tire tread. The electrically conductive materialcan be a liquid (e.g., carbon black mix in a volatile liquid) that formsan electrically conductive body upon evaporation. Alternatively, theelectrically conductive material can be a dry mixture, such as powder(e.g., carbon black mix powder).

The coating, piercing and withdrawing steps can be continuously repeatedand a plurality of pins can be sequentially coated, used to pierce thetire tread, and then withdrawn. For example, the plurality of pins canbe mounted on the circumference of a wheel which is turned by movementof the tire tread, preferably at fixed distances so that piercing willoccur at regular intervals. The pins can be attached to an adapter rimfor the wheel and can comprise the distal portion of screws threadedinto openings on the rim or posts press-fit into openings on the rim.The pins can be arranged in a single row or in a plurality of staggeredor aligned rows. A transfer reel, which is turned by rotation of thewheel, can be used to coat the pins prior to the piercing step.

The piercing step can be performed on a central region of the tire treadand in such a manner that the electrically conductive body can form acontinuous electrical path (or a bridge) between a rolling surface and acarcass of a tire.

These and other features of the invention are fully described andparticularly pointed out in the claims. The following descriptiveannexed drawings set forth in detail a certain illustrative embodimentof the invention, this embodiment being indicative of but one of thevarious ways in which the principles of the invention may be employed.

DRAWINGS

FIGS. 1A-1D are schematic views of the steps of a method of introducinga conductive material into a tire tread according to the presentinvention.

FIG. 2 is a schematic view of a tire tread into which conductivematerial has been introduced by the method of the present invention.

FIG. 3 is a top view of a machine for making an anti-static tire treadaccording to the present invention.

FIG. 4 is a front view of the machine.

FIG. 5 is an isolated front view of a part of the machine, namely anadapter rim.

FIG. 6 is an enlarged portion of FIG. 5.

FIG. 7 is an isolated front view of another adapter rim.

FIG. 8 is an enlarged portion of FIG. 7.

FIGS. 9A-9C are top views of alternate forms of the adapter rim.

DETAILED DESCRIPTION

Referring now to the drawings, and initially to FIGS. 1A-1D, a method ofmaking an anti-static tire tread according to the present invention isshown. In this method, a pin 10 is coated with an electricallyconductive material M. (FIG. 1A.) The coated pin pierces an extrudedtire tread to form an opening 12 of the desired depth. (FIG. 1B.) Thecoated pin 10 is then withdrawn and the material M remains in thepierced opening 12 of the tire tread T. (FIG. 1C.) If the conductivematerial M is a liquid (e.g., carbon black mix in a volatile liquid) itforms a conductive body 14 upon evaporation. If the conductive materialM is a dry mixture (e.g., carbon black mix powder), the powder remainsin the pierced opening 12 to form the electrically conductive body 14.(FIG. 1D.) The pin 10 can then be re-coated with the material M and thecycle repeated to produce a plurality of conductive bodies 14.

Referring now to FIG. 2, a central region the tire tread T is shownafter a plurality of conductive bodies 14 have been formed therein. Theelectrically conducting bodies 14 are uniformly spaced and of asufficient depth so that they will form a continuous electrical pathbetween the rolling surface and the carcass of the tire. In thepreferred embodiment, each electrically conducting body 14 is made froma carbon black mix with an electrical resistivity of less than 10⁹ohms×cm.

Referring additionally to FIGS. 3 and 4, a machine 20 for performing themethods of the present invention is shown. The machine 20 comprises aframe 22, a wheel assembly 24, and a supply system 26. The frame 22positions the wheel assembly 24 above a conveyor 28 for the tire treadT. The wheel assembly 24 supports the pins 10 and moves them to performthe piercing and withdrawing steps. The supply system 26 coats the pins10 with the electrically conductive material M prior to the piercing andwithdrawing steps.

The illustrated frame 22 comprises end members 32 positioned on eitherside of the conveyor 28, shafts 34 extending between the end members 32,and a top member 36 extending between the shafts 34. The top member 36can be selectively slidable on the shafts 34 for transverse positioningof the wheel assembly 24 relative to the tire tread T. The frame 22 caninclude a lift for raising and lowering the wheel assembly 24 relativeto the conveyor 28. For example, the illustrated lift comprises a liftbar 38, a cylinder 40 coupled to the lift bar 38, and guide rods 42attached to the lift bar 38 and slidably received by the top framemember 36.

The wheel assembly 24 comprises a wheel 44 and a spindle 46 rotatablymounting the wheel 34 to the lift bar 38. The wheel 44 is positionedrelative the tread conveyor 28 so that it will be turned by the actionof the tread T passing therebeneath. The pins 10 are mounted on thecircumference of the wheel 44 at fixed distances so that the turning ofthe wheel 44 will cause the pins 10 to pierce the tread T at regularintervals.

In the illustrated embodiment, the pins 10 are part of an adapter rim 48which is wrapped around the wheel 44. The pins 10 can comprise thedistal portions of posts 50 which are friction fit into openings 52 inthe rim 48. (See FIGS. 5 and 6.) Alternatively, the pins 10 can comprisethe distal portions of socket head cap screws 50 and the openings 52 inthe rim 48 can be threaded and counterbored for receipt thereof. (FIGS.7 and 8.) The pins 10 can be arranged in a single row (FIG. 9A) or aplurality of rows (FIGS. 9B and 9C). If arranged in a plurality of rows,the pins 10 can be transversely aligned (FIG. 9B) or staggered (FIG.9C). In any case, the pins 10 can be textured to facilitate the coatingprocess.

The supply system 26 comprises a tank 60, a bracket 62 that fixedlymounts the tank 60 to the lift bar 38, a transfer reel 64, and a spindle66 that rotatably mounts the reel 64 to the lift bar 38. The tank 60contains the electrically conductive material M and a belt 68 connectsthe spindle 46 to the spindle 66 so that turning of the wheel 44 willresult in rotation of the reel 64. The transfer reel 64 includes a slotwhich captures the material M as it passes through the tank 60 and whichreceives the pins 10 as the reel 64 passes by the wheel 44.

Accordingly, as the tread T is linearly moved by the conveyor 28, thewheel 44 is turned. As the wheel 44 turns, the transfer reel 64 alsorotates whereby the material M from the tank 60 is coated on the pins10. The turning of the wheel 44 also causes the coated pins 10 to piercethe tread T at regular intervals, and, further turning of the wheel 44causes the pin 10 to be withdrawn with the material M remaining in thepierced opening. As the wheel 44 continues to turn, the pins arere-coated with the material M and the cycle repeated.

Although the invention has been shown and described with respect to acertain preferred embodiment, obvious and/or equivalent alterations andmodifications will occur to others skilled in the art upon the readingand understanding of this specification. The present invention includesall such equivalent alterations and modifications and is limited only bythe scope of the following claims.

1. An apparatus for introducing a material into an article, theapparatus comprising: a frame; a wheel rotatably mounted to the frame; aplurality of pins mounted on the wheel and disposed radially outwardtherefrom; and a supply system positioned adjacent to the wheel andconfigured to coat at least one pin with the material, wherein thesupply system includes a transfer reel rotatably mounted to the frame,wherein the transfer reel includes at least one slot which receives thepins and contains the material so that at least one pin can be coatedwith the material as the reel passes by the wheel, and wherein, uponrotation of the wheel, at least one pin coated with the material piercesthe article, thereby leaving at least a portion of the material in thearticle after the pin is withdrawn therefrom.
 2. The apparatus of claim1, wherein the transfer reel is rotatably mounted to the frame and iscoupled the wheel, such that turning of the wheel causes rotation of thetransfer reel.
 3. The apparatus of claim 1, wherein the transfer reelslot captures the material as it passes through the supply system. 4.The apparatus of claim 1, further comprising a conveyor, whereinmovement of the article on the conveyor causes the wheel to turn.
 5. Theapparatus of claim 1, wherein the pins are arranged in a single row. 6.The apparatus of claim 1, wherein the pins are arranged in a pluralityof axially spaced rows.
 7. The apparatus of claim 6, wherein the pins ineach row are transversely aligned.
 8. The apparatus of claim 6, whereinthe pins in each row are transversely staggered.
 9. The apparatus ofclaim 1, wherein the frame further comprises a lift for raising andlowering the wheel relative to a conveyor for moving the article. 10.The apparatus of claim 9, wherein the lift further comprises a lift barand at least one guide rod attached to the lift bar and the frame. 11.The apparatus of claim 10, wherein the wheel is rotatably mounted to thelift bar.
 12. The apparatus of claim 1, wherein the supply systemfurther comprises a tank that contains the material.
 13. The apparatusof claim 1, wherein the wheel is positioned above the article.
 14. Anapparatus for introducing electrically conductive material into a tiretread, the apparatus comprising: a frame having a lift mechanism; awheel rotatably mounted to the lift mechanism such that the wheel isconfigured to be raised and lowered; a plurality of circumferentiallyspaced pins mounted on the wheel and disposed radially outwardtherefrom; and a supply system positioned adjacent to the wheel andconfigured to coat at least one pin with the electrically conductivematerial, wherein the supply system includes a transfer reel rotatablymounted to the frame, wherein the transfer reel includes at least oneslot which receives the pins and contains the material so that at leastone pin can be coated with the material as the transfer reel passes bythe wheel, and wherein, upon rotation of the wheel, at least one pincoated with the electrically conductive material pierces the tire tread,thereby leaving at least a portion of the electrically conductivematerial in the tire tread after the pins are withdrawn therefrom. 15.The apparatus of claim 14, wherein the transfer reel is rotatablymounted to the frame and is coupled to the wheel, such that turning ofthe wheel causes rotation of the transfer reel.
 16. The apparatus ofclaim 14, wherein the transfer reel slot captures the electricallyconductive material as it passes through the supply system.
 17. Theapparatus of claim 14, wherein the supply system includes a tank thatcontains the electrically conductive material.
 18. The apparatus ofclaim 14, wherein one or more of the pins include a textured portion tofacilitate the coating process.
 19. The apparatus of claim 18, whereinthe textured portion includes a diamond knurl.
 20. The apparatus ofclaim 14, wherein the wheel is positioned above the tire tread.